1. Technical Field
This invention relates to magnetic tape devices and particularly to magnetic tape devices improving a reliability of data which are recorded on magnetic tapes.
2. Background Art
A magnetic tape device is a device for recording or reproducing data on a magnetic tape with magnetic head. The magnetic tape device is used for recording data which is managed in server computer as backup data. One of constitutions of the magnetic tape device is a helical scanning method. The helical scanning method is a method for arranging a plurality of magnetic heads around a head drum, and recording and reproducing data in track on tape by rotating the head drum and running the magnetic tape around the head drum as shown in FIG. 1 described below. Another constitution of the magnetic tape device is a linear recording method. There is provided a magnetic head assembly including a plurality of magnetic heads in the linear recording method. Then a device records or reproduces data in a running magnetic tape by moving the magnetic head assembly vertically with respect to a width of the magnetic tape as shown in FIG. 12 described below.
According to the magnetic tape device including a plurality of magnetic heads described above, there is a problem of failing in processing of reading data. More specifically, if a problem occurs in a part of magnetic heads or the data cannot be read partially due to a dirt or a scratch on the tape, the processing can be failed even if remaining data can be read normally. That is, there is a problem that reliability of a conventional magnetic tape device is lacked because the data cannot be read in case that one of a plurality of magnetic heads crashes or a dirt is attached to a part of the tape although the device includes a plurality of magnetic heads.
As the art for resolving the problem, Japanese Unexamined Patent Application Publication No. 5-282608 (Koyama) discloses the magnetic tape device including a plurality of magnetic heads which records data and duplicated data in adjacent tracks on a magnetic tape simultaneously. The magnetic tape device gives the recording data redundancy by recording the duplicated data.
However in the art of Koyama, data and duplicated data having redundancy are recorded in the adjacent tracks. Therefore, both data cannot be read in case that an error in reading is occurred by a dirt or a scratch in adjacent data areas on the magnetic tape. Then there is raised a problem that the reliability cannot be improved. Further there is also a problem that amount of data capacity is enormous because a copy of recording target data is recorded in addition to the original data.